February 23, 2016

Climate scientist Mike Mann is a favorite target for climate denial paranoia sites – because climate denial PR masterminds know the power of a good graphic when they see it. The Mann, Bradley, Hughes paper in 1999, which showed for the first time in stunning graphic terms what a sudden spike in global temperatures looked like, has been all the more enraging to the science illiterati, in that, it keeps being confirmed by subsequent research. The more you look, the more signs of global temp rise you find.

In the second study, scientists reconstructed the level of the sea over time and confirmed that it is most likely rising faster than at any point in 28 centuries, with the rate of increase growing sharply over the past century — largely, they found, because of the warming that scientists have said is almost certainly caused by human emissions.

They also confirmed previous forecasts that if emissions were to continue at a high rate over the next few decades, the ocean could rise as much as three or four feet by 2100.

Experts say the situation would then grow far worse in the 22nd century and beyond, likely requiring the abandonment of many coastal cities.

The findings are yet another indication that the stable climate in which human civilization has flourished for thousands of years, with a largely predictable ocean permitting the growth of great coastal cities, is coming to an end.

“I think we can definitely be confident that sea-level rise is going to continue to accelerate if there’s further warming, which inevitably there will be,” said Stefan Rahmstorf, a professor of ocean physics at the Potsdam Institute for Climate Impact Research, in Germany, and co-author of one of the papers, published online Monday by an American journal, Proceedings of the National Academy of Sciences.

In a report issued to accompany that scientific paper, a climate research and communications organization in Princeton, N.J., Climate Central, used the new findings to calculate that roughly three-quarters of the tidal flood days now occurring in towns along the East Coast would not be happening in the absence of the rise in the sea level caused by human emissions.

A group of scientists says it has now reconstructed the history of the planet’s sea levels arcing back over some 3,000 years — leading it to conclude that the rate of increase experienced in the 20th century was “extremely likely” to have been faster than during nearly the entire period.“We can say with 95 percent probability that the 20th-century rise was faster than any of the previous 27 centuries,” said Bob Kopp, a climate scientist at Rutgers University who led the research with nine colleagues from several U.S. and global universities. Kopp said it’s not that seas rose faster before that – they probably didn’t – but merely that the ability to say as much with the same level of confidence declines.

The study was published Monday in the Proceedings of the National Academy of Sciences.

Seas rose about 14 centimeters (5.5 inches) from 1900 to 2000, the new study suggests, for a rate of 1.4 millimeters per year. The current rate, according to NASA, is 3.4 millimeters per year, suggesting that sea level rise is still accelerating.

surprisingly, the study blames the anomalous 20th-century rise on global warming — and not just that. It also calculates that, had humans not been warming the planet, there’s very little chance that seas would have risen so much during the century, finding that instead of a 14 centimeter rise, we would have seen somewhere between a 3 centimeter fall and a 7 centimeter rise.

The new work is particularly significant because, in effect, the sea level analysis produces a so-called “hockey stick” graph — showing a long and relatively flat sea level “handle” for thousands of years, followed by a “blade” that turns sharply upwards in very recent times.

The discovery of such patterns itself has a long history, going back to a 1998 study by climate researcher Michael Mann of Penn State University and two colleagues — who found a “hockey stick” graph for the planet’s temperature, rather than for its sea level. Since then the “hockey stick,” in its various incarnations, has come in for voluminous criticism from skeptics and doubters of human-caused climate change — even as multiple scientists have continued to affirm the conclusion that the last 100 years or so are way out of whack with what the planet has seen in the past thousand or more.

Fig. 1 Reconstruction of the global sea-level evolution based on proxy data from different parts of the world. The red line at the end (not included in the paper) illustrates the further global increase since 2000 by 5-6 cm from satellite data.

This week, a paper will appear in the Proceedings of the National Academy of Sciences (PNAS) with the first global statistical analysis of numerous individual studies of the history of sea level over the last 2500 years (Kopp et al. 2016 – I am one of the authors). Such data on past sea level changes before the start of tide gauge measurements can be obtained from drill cores in coastal sediments. By now there are enough local data curves from different parts of the world to create a global sea level curve.

Let’s right away look at the main result. The new global sea level history looks like (the graph above).

To understand this curve we need to know one thing. There is a remaining uncertainty in the linear trend over the whole period. This is because in many places of the world slow processes, especially continuing land uplift or subsidence after the end of the last Ice Age, cause a sea-level trend uncertainty (because land subsidence is not the same as sea level rise, this needs to be subtracted). It is therefore the fluctuations around the linear trend which are the most robust aspect of these data. The uncertainty in the trend is small, only 0.2 mm/year (the current sea level rise is 3 mm/year). But even a small steady trend of 0.2 mm/year amounts to half a meter during 2500 years. For the graph above, this means that the correct curve could be “tilted” a little to the left or right. This would, for example, change the relative global sea level in 2000 compared to the Middle Ages – this relative height does not belong to the robust results, as stated in the paper.

In contrast, a robust result is the fact that sea level has risen more during the 20th century than during any previous century. (This statement is true regardless of an additive trend.) A good way to show this is the following graph.

The current research confirms an earlier 2000 year graph from Kemp et al, 2011.

I know you like to start the day by ruining ours, Peter, but this is too much. First an excellent piece on declining snow cover and arctic sea ice, now SLR hockey sticks. Make our day complete by posting something with a picture of Cruz and quoting him on climate change, why don’t you? I’d go back to bed and pull the covers over my head, but I’m going to have a tooth pulled later this AM—-that’s just to make sure this continues to be a “fun” day.

And the folks in NC are finally starting to realize that SLR is real and accelerating, in spite of the efforts by the lobbyists to get NC to pass laws stating that SLR simply wouldn’t be allowed there because it would negatively impact real estate values.

And remember the assertions of no increase in the rate of SLR from that moron Dave Burton, the so-called “science advisor” for the NC deniers? He apparently has little credibility in NC any more, and has been reduced to making moronic parrot comments on echo chamber denier sites like Steve Milloy’s junkscience.

(Anyone who visits that link should note the comment from the guy who says that SLR is occurring because underwater volcanoes are forming everywhere and displacing water upward. Why aren’t any Crockers smart enough to have thought of that?)

Good ol’ Dave Burton! Spouting complete nonsense over there. I wrote a couple of comments there, which I doubt will be published, or believed. Just in case anyone is interested, and in the hopes D.B. might be lured into response here, here they are (Feel free to delete these, Peter):

“…once we declare roundly that there is no Global Temperature… “

I, and many others, have roundly declared that that the Sun revolves around the Earth. But roundly declaring a supposed truth is not enough – one needs to publish evidence of claims and subject those claims to peer review criticism.

No doubt that paper is being prepared for publication in a peer-reviewed scientific journal? Because self-publishing a screed ( Amazon Best Sellers Rank: #1,357,100 in Books) is not the same thing.

“… because gravity tends to even out the effects of additions or removals of water from the oceans. That’s a big advantage of sea-level measurements, compared to temperature measurements. It means any long-term acceleration or deceleration in the rate of sea-level rise will be evident at all high-quality, long-term tide gauges, everywhere in the world.”

Except it doesn’t, and your claim that an increase in SLR will be seen equally all around the world is absurd and easily seen to be absurd – because when we look at SLR records it simply has not been the case, and still is not the case, and never will be the case.

There are numerous influences on local SLR which work against an even global SL change, like differential heating, the fact that the Earth is spinning, the mass of local continents and ice sheets, local elevation changes in land masses. etc. That you would even imply that gravity predominates and that SLR should be consistent all around the world demonstrates that you either don’t know very much about the topic, or are actively trying to hornswaggle the folks here, Dave.

“The difference is that the current +1.5 mm/year is catastrophic and caused by human release of CO2, and the +1.5 mm/year eighty years ago was natural and inconsequential. “

Except that your numbers are wrong and your categorization of SLR eighty years ago as being “natural” is false. Current SLR is NOT 1.5mm/year. In fact, SLR has not been that slow in decades. Here are the correct figures:

Notice anything about those numbers? They are not just rising – the rise itself is accelerating. How could someone who promotes themselves as an ‘expert’ on SLR be so poorly informed?

As for your claim that eighty years ago, SLR was from natural causes, that is belied by the evidence. Eighty years ago was 1935, and SLR was double that of the already accelerated rate of 1870-1924. Before 1800, Global Sea Level was actually going down slightly.

Eighty years ago was about 120 years into the Industrial Revolution when fossil fuels started being burned at a significant clip, so the increased SLR of eighty years ago was not “natural” at all – it was due to increased greenhouse gases. Just like today.